Coarse screening dry particulate materials



Jan. 15, 1963 Filed March 28, 1960 c. E. JOHANNlNGMEiER 3,073,449

COARSE SCREENING DRY PARTICULATE MATERIALS 2 Sheets-Sheet l INVENTORJan. 15, 1963 c. E. JOHANNlNGMEiER ,4

COARSE SCREENING DRY PARTICULATE MATERIALS Filed March 28, 1960 2Sheets-Sheet 2 INVENTOR United States corporation of New York Filed Mar.28, 1960, Ser. No. 18,032 3 Claims. (Cl. 209288) The instant inventionrelates generally to the art of coarse screening dry particulatematerials especially as employed in conjunction with a rotary dryer toeffect separating of larger sized particles and lumps from the rotarydryer material discharge. More specifically, the invention is directedto apparatus of the grizzly bar type for effecting coarse screeningwhich is mountable on the discharge end of a rotary dryer to efiect anactive coarse screening operation on the material discharge as the dryerrotates.

As used hereinafter, the term grizzly or grizzly bar screen is employedas best denoting the general character of the screen apparatus formingthe subject of the instant invention. As is well recognized, the termgrizzly or grizzly bar screen is descriptive of apparatus having a heavyscreening surface usually made of spaced parallel straight bars suchthat a corse screening operation is effected where bulk particulatematerial having various sized particles and lumps is discharged onto thescreening surface.

Considering the problem which confronted applicant herein, it was founddesirable to provide a means for separating larger particles and lumpsof particulate material being discharged from a rotary dryer so that thefinal product might have a more limited range of particle sizes and befree of large lumps which may build up during drying to be present inthe material which is discharged from the dryer. In seeking a solutionto this problem, the instant invention was conceived. Generally, theinvention may be described as efifectively utilizing the rotary movementof a dryer shell to perform an active coarse screening operation andautomatically separate lumps or larger particles, carrying them on pastthe final product chute so that the desired separating action isachieved. Not only does utilization of the rotary movement of the dryershell promote the coarse screening operation but also such movementcontributes to a self-cleaning of the apparatus used to effect thecoarse screening.

Accordingly, it is an object of the instant invention to provide animproved coarse screening apparatus mountable on the end of a rotarydryer to effect, in conjunction with dryer rotation, separation of lumpsand larger particles from the final product.

It is a further object of the instant invention to provide for coarsescreening of dry particulate materials embodying apparatus of thegrizzly bar screen type mounted on the end of a rotary dryer to rotatetherewith whereby self-cleaning of the grizzly bar screen apparatus, inconjunction with the coarse screening operation to remove lumps andlarger particles, is effected.

Another object of the instant invention is to provide a grizzly barscreen which is rotatable on the end of a rotary dryer and incorporatesmeans to retain a minimum bed depth within the dryer.

It is also an object of this invention to provide a rotary grizzly barscreen incorporating lifter elements to promote agitation and removal oflumps and larger particles in conjunction with a coarse screeningoperation.

The above and other more specific objects of the instant invention willbe appreciated by reference to the specific description of a particularembodiment of the instant invention. It is to be understood that theillustrated and described embodiment is by no means to be 3,073,44gPatented Jan. 15, 1963 considered to be limiting on the scope of theinstant invention, but rather is only illustrative of a structureincorporating the principles of the instant invention. The invention maybe best understood by reference to the accompanying drawings in which:

FIGURE 1 is a side elevational view of the invention with parts shown insection taken on line 11 of FIG- URE 2, and

FIGURE 2 is an end elevational view of the structure shown in FIGURE 1with parts thereof broken away and shown in section.

Referring to the drawings and specifically to FIGURE 1, a rotary dryerIt with the end of the dryer shell 1'1 being shown, has mounted thereona rotary grizzly bar screen 12 described in more detail hereinafter.

Only the end portion of the dryer shell 11 is shown since theconstruction of the dryer may take a variety of forms well known in theprior art. The dryer 10 is rotatably mounted as by means of acylindrical track 13 encircling the shell 11 and rotatably supported onsuitable rollers 14 mounted on base 15. The dryer is driven by suitablemeans (not shown) to rotate in the direction of arrow A on FIGURE -2,whereby the material M being dried, tumbles within the rotating shell 11upon rotation of the dryer and progressively moves toward the dryerdischarge end on which the grizzly bar screen 12 is mounted.

Grizzly bar screen 12 includes a sectionalized annular ring 20 which isattached at its outer perimeter to the open discharge end of the dryershell 11. It will be understood that means such as welding, bolting,etc., may be employed to mount ring 20 on the end of shell 11 and thatspecific illustrations of the various fastening approaches are notnecessary. The radial width of ring 20 determines the bed depthmaintained within the dryer 10. As shown in FIGURE 1, material Maccumulates within the dryer shell 11 up to the level of the innerperimeter of ring 20 above which level the rotary action of the dryerspills the material over the lip 21 of ring 20.

The grizzly bar screen 12. is formed in four quadrant sections orsub-assemblies as shown in FIGURE 2. Each quardant section includes anarcuate portion of ring 29 with support members 22 extending outwardlyfrom the outer surface of and at the outer perimeter of each end of eacharcuate portion of ring 20. An additional support member 23 is providedfor each of the sections of the grizzly bar screen such additionalmember 23 being disposed midway of the arcuate section length betweensupport members 22.

The outer ends of the support members 22 and 23 are secured to anannular ring 24. Ring 24, like ring 20, is formed in four arcuate 90portions with each portion of ring 24 having outwardly extending flanges25 at its opposite ends to facilitate bolting together the quadrantscreen section by suitable fasteners 26. Of course, the quadrantsections may be fastened together into a cylindrical configuration bysuitable means other than the flanges and bolting shown.

Each of the support members 22 and 23 has secured thereto arcuatelycurved grizzly bars 30, these bars extending parallel to each other andbridging the space between adjacent support members 22 and 23. Thegrizzly bars 30 form the coarse screening surface onto which thematerial M passes after flowing over lip 21. The spacing of the barspermits the appropriate sized smaller particles to pass therebetween anddischarge as the final product through an appropriate product chute 35.The chute 35 is mounted at the lower portion of the dryer she-ll and mayappropriately enclose a limited extent upwardly on the sides of thegrizzly bar screen to collect all particles passing between the grizzlybars 30 3 as the dryer with the grizzly bar screen mounted thereinrotates.

The larger particles and lumps which cannot pass between the grizzlybars will collect on the radially inner edges of bars 30 and passoutwardly as the apparatus rotates, eventually passing Over the innerperiphery of ring 24 to be collected and carried away through a suitablechute 40. W

Since the grizzly bar screen 12 rotates with dryer 10, the material Mdischarged thereinto will be agitated and carried up the side of thescreen 12 in the direction of rotation. Since the screen 12 continues torotate, there will be in effect a self-cleaning action as the bars moveto the top of their rotary path whereat any material collected orlightly wedged between the bars tends to fall back to the lower portionof the screen 12.

To promote agitation and rapid removal of lumps, and larger particles,there are provided, mounted at circumferentially spaced positions aroundthe interior of annular grizzly bar members, a series of lifter elements45. These lifter elements are secured, as by welding, to the radiallyinner edges of grizzly bars 30 to extend diagonally across each group ofgrizzly bars. In the illustrated embodiment, twelve lifter elements areequally distributed around the annular grizzly bar members with eachelement being disposed at an angle of 60 to the longitudinal dimensionof the grizzly bars 30 to which it is secured.

The lifter elements 45 perform a particular function in conjunction withthe coarse screening operation as the grizzly bar screen rotates withthe dryer. For those larger particles and lumps that do not readily passbetween grizzly bars 30 and into product chute 35, the lifter elements45 tend to carry such larger particles and lumps up the side of thescreen in the direction of rotation. The inclination of the lifterelements relative to the grizzly bars and to the direction of rotationof the dryer shell 11, which would be counterclockwise as shown by arrowA on FIGURE 2, is such that the material carried up the side of thescreen as it rotates, tends to flow along the inclined lifter elementstoward the Outer end of screen 12 to pass over the inner periphery ofring 24. This agitates the material to make for more eltective screeningand speeds up removal of the lumps and larger particles from the dryerdischarge material.

Although I have shown and described a certain embodiment of myinvention, it will be understood that I do not wish to be limited to theexact construction shown and described, but that various changes andmodifications may be made without departing from the spirit and scope ofthe invention as defined in the appended claims.

I claim:

1. Apparatus for effecting coarse screening of dry particulate materialscomprising a tubular dryer shell mounted to be rotable about itslongitudinal axis and having a discharge aperture at one end thereof, anannular ring mounted on said one end and having a radial width torestrict said discharge aperture and retain a predetermined bed depth ofmaterial within said dryer shell, a series of generally annular grizzlybar members mounted outwardly of said ring with the centers of curvatureof said annular members coinciding with said longitudinal axis, saidmembers being parallel to one another to provide spaces between adjacentmembers for passage of smaller particles radially outwardly through saidspaces while larger material particles and lumps are retained on theradially inner edges of said members, a plurality of lifter elementssecured at circumferentially spaced positions to extend generallytransversely of said radially inner edges of said members and diagonallyrelative to the planes of the parallel grizzly bar members, said annularring providing at the inner perimeter thereof an opening for materialflowing from said dryer shell into one end of said series of grizzly barmembers, and outlet means at the opposite end of said series of grizzlybar members for discharge of said larger material particles and lumpsfrom said radially inner edges of said members.

2. A grizzly bar screen adapted to be mounted on the discharge end of arotary dryer for rotation therewith comprising a series of generallyannular grizzly bar members, means interconnecting said members into agenerally cylindrical assembly with the centers of curva ture of saidannular members coinciding with the axis of said cylindrical assemblyand said members parallel to one another to provide spaces betweenadjacent members for passage of smaller material particles radiallyoutwardly through said spaces while larger material particles and lumpsare retained on the radially inner edges of said members, a plurality oflitter elements secured at circumferentially spaced positions to extendgenerally transversely of said radially inner edges of the members insaid assemby and diagonally relative to the planes of the parallelgrizzly bar members, means at one end of said assembly for connectingsaid screen to the discharge end of a rotary dryer, and outlet means atthe opposite end of said assembly for discharge of said larger materialparticles and lumps from said radially inner edges of said members.

3. A grizzly bar screen adapted to be mounted on the discharge end of arotary dryer for rotation therewith comprising groups of arcuatelycurved grizzly bars, means connecting the bars of each group parallel toone another to form a sub-assembly with arcuately extending spacesbetween adjacent bars for passage of smaller material particles radiallyoutwardly through said spaces while larger material particles and lumpsare retained on the radially inner edges of said bars, a plurality oflifter elements secured at spaced positions along said radially inneredges of the bars in each sub-assembly to extend generally transverselyof the bars in each subassembly and diagonally relative to the planes ofthe parallel grizzly bars, means connecting adjoining ends of saidsub-assemblies together to provide an assembly having a cylindricalconfiguration with parallel spaced generally annular grizzly barmembers, with circumferentially extending spaces between adjacentmembers, an annular ring at one end of said assembly for connecting saidscreen to the discharge end of a rotary dryer, said ring having a radialwidth to retain a predetermined bed depth of material within the rotarydryer shell with the inner perimeter of said ring forming an inlet formaterial to said assembly from the dryer, and outlet means at theopposite end of said assembly for discharge of said larger materialparticles and lumps from said radially inner edges of said bars.

References Cited in the file of this patent UNITED STATES PATENTS 46,323Bulsley Feb. 14, 1865 1,312,173 Gerlach Aug. 5, 1919 1,614,364 HidouxJan. 11, 1927 2,450,980 Moyer Oct. 12, 1948 2,543,898 De Vaney Mar. 6,1961

2. A GRIZZLY BAR SCREEN ADAPTED TO BE MOUNTED ON THE DISCHARGE END OF AROTARY DRYER FOR ROTATION THEREWITH COMPRISING A SERIES OF GENERALLYANNULAR GRIZZLY BAR MEMBERS, MEANS INTERCONNECTING SAID MEMBERS INTO AGENERALLY CYLINDRICAL ASSEMBLY WITH THE CENTERS OF CURVATURE OF SAIDANNULAR MEMBERS COINCIDING WITH THE AXIS OF SAID CYLINDRICAL ASSEMBLYAND SAID MEMBERS PARALLEL TO ONE ANOTHER TO PROVIDE SPACES BETWEENADJACENT MEMBERS FOR PASSAGE OF SMALLER MATERIAL PARTICLES RADIALLYOUTWARDLY THROUGH SAID SPACES WHILE LARGER MATERIAL PARTICLES AND LUMPSARE RETAINED ON THE RADIALLY INNER EDGES OF SAID MEMBERS, A PLURALITY OFLIFTER ELEMENTS SECURED AT CIRCUMFERENTIALLY SPACED POSITIONS TO EXTENDGENERALLY TRANSVERSELY OF SAID RADIALLY INNER EDGES OF THE MEMBERS INSAID ASSEMBY AND DIAGONALLY RELATIVE TO THE PLANES OF THE PARALLELGRIZZLY BAR MEMBERS, MEANS AT ONE END OF SAID ASSEMBLY FOR CONNECTINGSAID SCREEN TO THE DISCHARGE END OF A ROTARY DRYER, AND OUTLET MEANS ATTHE OPPOSITE END OF SAID ASSEMBLY FOR DISCHARGE OF SAID LARGER MATERIALPARTICLES AND LUMPS FROM SAID RADIALLY INNER EDGES OF SAID MEMBERS.